A clean file is the difference between a print that comes out perfectly and one that fails, costs more than it should, or arrives the wrong size. Here's everything you need to get right before you upload — explained for normal people, not just CAD nerds. Already have a file? Run the free STL checker →
STL files don't record their units. A model designed in inches can be read as millimetres and arrive 25× too small — this is the number-one cause of "my print came out tiny." Always export at the real-world size you want, in millimetres, and sanity-check the dimensions shown in the quote before you order.
The model needs to be a single solid shell with no holes, gaps, or overlapping/flipped faces, so the slicer can clearly tell the inside from the outside. "Non-manifold" geometry — stray edges, internal faces, zero-thickness surfaces — confuses the slicer and causes failed or weird prints. Many small issues can be auto-repaired; big ones we'll flag before you pay.
A wall has to be more than a couple of printed lines thick to survive. For FDM, keep walls at least 0.8–1.2 mm. Knife-thin edges, wafer-thin fins and tiny raised text often won't print cleanly — thicken them, or emboss/engrave text a little deeper. Our STL checker highlights walls that are too thin.
Printers build up layer by layer, so any face leaning past roughly 45° from vertical needs temporary support material underneath it. Support is printed then removed and thrown away — but you still pay for that plastic and it can mark the surface. Reorienting the model or tweaking the design to reduce steep overhangs saves money and gives a cleaner finish.
Export as STL (3MF and OBJ also work) at a sensible resolution — high enough that curves look smooth, but not so extreme that the file becomes huge and slow for no visible benefit. If you only have a CAD file like STEP, export an STL from your software first. Then give it a final check before uploading.
Free model sites like Printables, MakerWorld and Thingiverse have millions of print-ready STLs. Download, then upload it here for a quote.
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Upload your STL and we'll check the size, estimate the weight and support, and give you a firm price in seconds. Not sure about your file? We'll take a look before you pay.